what are the characteristics of database approach
Today we'll be learning about characteristics of database approach so there are total four characteristics of database approach first characteristic is called self-describing nature of database system the second one is called insulation between programs and data and data abstraction third one is called support of multiple views of the data and the final and the fourth one is called sharing of data and multi-user transaction processing
Alright so these are the four characteristics that you need to understand
now we will look at them in details one by one so let's look at the first characteristic
self-describing nature now what do you mean by self describing each other what do you think it means
okay describing nature means the database system in DBMS that is it does not only contain the database the database system does not only contain the database but also the information about the constraints and the structure of the database okay so it is describing itself like what is the structure of the database what are the constraints of the database and so on so this is called self describing nature of DBMS this is the first characteristic now where is this information stored and what is this information odd so the information about constraints and the structure of the database is known as the metadata now where is this metadata store metadata is stored in something called as catalog okay so it is stored in catalog now why is this information stored in catalog now you need to understand that a general database system is created not for some specific application but for uses okay so then you create something for a general use the developers of the application or the program or the user needs to know about the structure and the constraints of the database so that they can create the program around it okay or specifically for it so hence to get this information about the structure and constraints of the database they need to reference the metadata hence it is stored in the catalog of the database now let's look at the second characteristic the second characteristics of DBMS approach is known as insulation between programs and data and data abstraction okay so what do you mean by insulation between programs and data and data abstraction so in a file system what happens is suppose you want to make some change in the file system database you have to make this change in the entire program just because you make the change in the database it won't be reflected in the program okay so what you have to do in the file system is you have to change the entire program based on the change that you do in the database but it's not the same case in DBMS in DBMS suppose you want to add another piece of data that is data type let's say date of birth or something like that okay all you have to do is go to the catalog and add another data type called data world and the whole changes will be reflected in the entire program you don't have to go and edit the entire program so what does that mean is by changing the data in the database the program does not get affected okay so that's why it's called insulation between programs and data and data abstraction all right now let's look at a third characteristic support of multiple views of the data so before learning the support of what do you mean by support of multiple views you need to know what our views of the data so a database has multiple users of course okay each user may need different view of the database now what do you mean by view of the database suppose there are there is a database of students information okay now a student can access the database that is view the database okay and he might get his attendance percentage or he might get his the schools that he has code in a subject whereas a teacher also has the access to the same database okay now the teacher wants to get the information about contact details of the parents that are there in the database but a student cannot get the same information as the teachers that is a student does not have that privilege is that a teacher should have so there is a different view for a student there is a different view for the teacher another thing that you need to understand that you know view the information that is there that that is shown is either derived from the database or it is stored in the database so basically let's say there is some information like the marks of the students okay now suppose a teacher wants to find what are the what is the average score of the entire class okay out of 100 now she will just ask or query the database for average score of the students she will get the result out okay now the teacher does not know whether the information is stored in the database or it is derived from the database that is the teacher does not know whether the average score of the class is stored in the database or the average score is calculated by the database and then displayed so that is something known as support of multiple views of the data so multiple views means different user will have different you of the data based on the privileges that are there to the user so let's look at the third characteristics sharing of data and multi-user transaction processing all right now sharing of data and multi-user transaction processing what do you mean by that a multi-user DBMS as the name suggests has multiple uses it must allow multiple users to access and use the database at the same time so it should allow multiple users to use the data at the same time this is a must when multiple applications use a single database to store and integrate in one single database so this is a necessity okay sharing and sharing of data and multi-user transaction processing this is a characteristics that a DBMS must have so that it becomes useful for multiple users okay now what do you need okay to do this to achieve this a concurrency control software must be equated alright so what do you mean by a concurrency control software okay a concurrency control soft is a software that will allow a user to access the data at the same time whereas other user will be able to use the database but not the same data okay once one user commits the changes then only the other person can come and add new changes or edit it okay so this is known as concurrency control now for this you have concurrency control software's they are also known as OLTP okay so why this concurrency control software exists they exist so that whenever a user uses the data it should be correct okay and update it they shouldn't be confusion like right now this data was X after two seconds the data is Y which one to choose okay hence once a user commits the changes then only other person can use it this is also known as acid properties that is we will talk about acid properties afterwards right not right now let's look at an example so that you understand better suppose you are trying to book a ticket on an online ticket booking website for a bus okay this is the seating arrangement for the bus and all seats are available when you go okay no you're like okay fine all seats are variable I will come after five minutes I will books typically after five minutes you come you see some seats have been booked that are there in the red have already been booked now you are like okay fine it's okay I'll book seat number one okay so you select seat number one we will see seat number one selected at the same time okay someone else also comes online and he wants to book seat number one as well but the system won't allow it the system will show seat one is not available kindly select another see to that person alright you have not yet completed the booking you have just select the book you just selected the seat okay but still the user won't be able to select the same seat as you okay this is known as concurrency control now if you book the ticket it's all fine the seating arrangement will look the same but suppose if you go in to book the ticket okay you're like okay fine I'll book the next day's ticket I won't select this safe so you cancel the booking now the CDs are get available so after some time it depends on the website maybe 15 is softener the seat is going to be made available again to users for booking now why this exists this exists because two users shouldn't be able to book one single seed in the name of two different users alright this is known as concurrency control and this is the fourth characteristic of the database approach so that's it for today
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